Aim of the study. To establish a Czech translation of the Western Ontario McMaster Universities Osteoarthritis Index (WOMAC), to find out its reliability, inner integrity, and the sensitivity to the changes induced by surgical treatment of the knee osteoarthritis. Methods. The questionnaire had been translated independently by three rheumatologists, and the final version was then designed after mutual discussion. This version was tested on a group of 50 patients with knee osteoarthritis (median age 75.5 years) indicated to the total joint arthroplasty. Index was tested twice prior operation, within the entry examination and after both one week and three months since the operation was performed. The mean value of the WOMAC, particularly WOMAC-A, WOMAC-B, and WOMAC-C indices, as well as each of the subsequently calculated indices were compared and correlated. Inner integrity of the questionnaire has been evaluated using inner associative analysis. Progression of the index values, particular indices, and each components followed by surgical treatment has been evaluated. Results. Fifty patients were enrolled into this study and 23 of them finished the follow up. WOMAC values, particular indices, and individual components, except one question, did not differ significantly and correlated with each other. Statistically significant correlations of each components and particular indices have been demonstrated using inner associative analysis. Surgical treatment was followed by significant decrease of the WOMAC index, particular indices WOMAC-A, WOMAC-B, and WOMAC-C as well as the individual components. Conclusion. The Czech linguistic validated version showed in this study high reliability, inner integrity as well as high sensitivity to the surgical treatment.

        Key words: knee osteoarthritis, functional involvement, WOMAC